Brewster's Law If the angle of incidence and the angle of refraction are complementary angles, the angle of incidence is referred to as the Brewster angle θ_B. The Brewster angle is related to the index of refractions of the two media, n₁ and n₂, by the equation n₁ sin θ_B = n₂ cos θ_B, where n₁ is the index of refraction of the incident medium and n₂ is the index of refraction of the refractive medium. Determine the Brewster angle for a light beam traveling through water (at 20°C) that makes an angle of incidence with a smooth, flat slab of crown glass.

Light sound, and other waves travel at different speeds, depending on the media (air, water, wood, and so on) through which they pass. Suppose that light travels from a point A in one medium, where its speed is v₁, to a point B in another medium, where its speed is v₂. Refer to the figure, where the angle θ₁ is called the angle of incidence and the angle θ₂ is the angle of refraction. Snell's Law, which can be proved using calculus, states that

The v_l/v₂ is called the index of refraction. Some values are given in the table shown to the right.

Transcribed Image Text:

sin 01 sin 02 V2 Angle of incidence A. Incident ray, speed v, Refracted ray, speed v2 "Angle of refraction